JPH01229472A - Noise reducing device for step motor - Google Patents

Abstract

PURPOSE:To decrease undesired vibration and therefore reduce noise by adding inertia to the shaft of a step motor to produce no torque coaxially to the step motor shaft after formation of the groove of a lead screw. CONSTITUTION:An inertia 18 is added to a lead screw 15. In other words, the inertia 18 is added coaxially to the screw 15 and works as the total inertia of a step motor 19 which produces no torque. As a result, the inertia 18 functions to change undesired intermediate resonance points at start/stop of the motor 19 and to improve the damping action to ensure smooth start characteristics. At the same time, the reaction caused by a carriage 12 at the stop time can be reduced. Furthermore, the motor 19 can be stabilized at a point having the energy of a low level with increase of the inertia at the drive side. Then hysteresis can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sudden noise reduction device for a step motor used in a floppy disk device or the like.

2. Description of the Related Art Conventionally, the step motor used in this type of floppy disk device has often been of the permanent magnet (PM type) type. By performing stepwise motion relative to the input, the track can be moved in proportion to the input pulse, and data can be recorded or reproduced.

Problems to be Solved by the Invention However, in conventional step motors, in order to achieve high speed, this was achieved by reducing the inertia of the rotor and by using magnets with a high energy product such as polar anisotropy. However, due to the relationship between output and load inertia, it is not possible to reduce noise due to vibrations associated with the Nakagusuku resonance band. Further, there is a problem in that it is not possible to reduce a stop position error (hysteresis) due to a difference in the rotation direction due to the balance with the load side.

The present invention solves these conventional problems.

The object of the present invention is to provide an excellent step motor recitation sound reduction device that can ensure low sound detection and high stop position accuracy.

Means for Solving the Problems In order to achieve the above object, the present invention
The inertia is coaxial with the rotor shaft of the step motor, which has grooves of -, and does not generate torque.
By adding it to the rotor or reed sleeve IJ, -, the Nakagusuku resonance band is changed and vibration is reduced.

Effects The present invention has the following effects due to the above configuration. That is, unnecessary vibrations generated when the rotor rotates and stops can be attenuated in a short time by lowering the vibration frequency not only by the rotor but also by the added inertia. Furthermore, unnecessary vibrations can be rapidly damped by transmitting vibrations from the load side in the opposite manner as described above.

Real thousand giants FIG. 1 shows an embodiment of the present invention.

Reference numeral 11 denotes a magnetic head for recording or reproducing, which is fixed to a carriage 12 . The carriage 12 moves along a guide shaft 13 to track a recording medium (not shown). 14 is a follower attached to the carriage 12, and is drawn into contact with the groove 16 of the lead screw 15 by a spring 17. 18 is an inertia added to the lead screw, and 19 is a step motor. Further, 20 is a step motor drive current υ, which is supplied to the step motor 1 from the step motor drive circuit 21 by the step motor control signal 22.
9.

Next, the operation of the above embodiment will be explained. According to the above embodiment, when the step motor control signal 22 is input to the step motor drive circuit 21, the step motor drive current 20 is output to the step motor 19.

The step motor 19 repeatedly rotates and stops in accordance with the step motor W dynamic current 20 to obtain a required rotation angle.

The lead screw 15 is connected to a step motor 19, and a follower 14 in contact with a groove 16 moves the carriage 12 and moves the magnetic head 11 to a desired track according to the guide shaft 13. The inertia 1-18 is coaxially attached to the screen 15 and operates as an inertia for the entire step motor that does not generate torque.

According to the embodiment described above, the inertia 18 changes the unnecessary mid-range resonance point when the step motor 19 is started or stopped, enhances the damping effect, provides smooth starting characteristics, and also It has the advantage of being able to reduce the reaction time. Further, according to the above embodiment, by increasing the inertia on the drive side, the step motor 19 can be stabilized at a stable point of lower energy, and hysteria can be reduced.

FIG. 2 shows the typical characteristics of the generated torque and rotation angle of a step motor. When inertia 18 is added, the stable point of the step motor 19 changes from ±0 to ±07.
and hysteresis.

FIG. 3 shows the main parts of another embodiment. In this embodiment, an inertia 34 is incorporated into a step motor 30, 32 is a stator, 33 is a rotor magnet, and 31 is an output shaft. shows. This embodiment has the advantage that it can be built into a step motor. Note that the inertia 34 in the embodiment shown in FIG.
It may be provided on the outer periphery or inner periphery of 3.

Effects of the Invention As is clear from the above-mentioned embodiments, the present invention is a step motor having an inertia that does not generate torque coaxially with the step motor shaft in which reed grooves are formed on the shaft of the step motor. This has the advantage of being able to reduce unnecessary vibrations and noise. Furthermore, since the step motor can be stopped at a lower energy level due to the reaction on the load side, hysteresis can be reduced and positioning accuracy can be improved.

Furthermore, depending on the mounting position of the inertia, it can also be effective as a limiter in the thrust direction of the step motor.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a step motor noise reduction device according to an embodiment of the present invention, Fig. 2 is a characteristic diagram showing the generated torque and rotation angle of the step motor, and Fig. 3 is an inside of the step motor of another embodiment. FIG. 11. Magnetic head, 12. Carriage, 13. Guide shaft, 14. Follower, 15. Lead screw, 16. Groove, 17. Wing, 18. Inertia, 19. Step motor, 20・・Step motor body current, 21・・Step motor drive circuit, 22・
Step motor control signal, ±0: Step motor stop range when there is no inertia, ±0'; Step motor stop range when inertia is added, 30...Step motor, 3
Treat screw shaft, 32, stator, 33
...Rotor magnet, 34...Inertia. Name of agent: Patent attorney Satoshi Nakao and one other person Figure 1! 4 7 Orowano 3 Inarshi Y Fig. 2 Fig. 3 &- I

Claims (1)

[Claims] Using a follower that contacts the groove of the lead screw,
The floppy disk device body, which moves the magnetic head for recording and reproduction to the required track for recording and reproduction, and the step motor shaft, in which the groove of the lead screw described above is formed on the shaft of the step motor, are coaxially connected without generating torque. and the inertia added to the shaft of the step motor,
A step motor noise reduction device that reduces unnecessary transient vibrations, reduces driving noise, and improves stopping accuracy.